What is Thalassemia?
All living tissues in the body require oxygen for normal metabolism. Oxygen molecules are carried to various tissues through the hemoglobin in the blood. Hemoglobin protein is made up of chains. Thalassemia results when congenital defects in the genes impair the chain production.
These genetic defects are usually inherited from one’s parents. Since we inherit two sets of genes – one from the mother and one from the father – chances of the offspring getting the disease would depend on the kind of genes it receives. It will take two defective genes to get the disease – which means that if both the father and mother have thalassemia, the child is sure to get it too. But if one received gene is normal, it will help the hemoglobin synthesis to be more or less normal, despite the defective gene. The child will thus not have thalassemic symptoms, though it will still carry that received defective gene: this condition is called a ‘trait’. If two such people with the ‘trait’ marry, there are chances their defective genes get carried to their offspring – which means that the child could get the disease even if the parents do not have it.
In India, there are about one lakh children suffering from thalassemia. Every year, upto 20,000 new cases are being diagnosed – in addition to about three crores already living with the trait.
Since hemoglobin is defective in thalassemia, problems arise from lack of sufficient oxygen delivery to the tissues. This leads to breathlessness and fatigue. The heart works much harder trying to supply more blood and may eventually give out. The body tries to compensate by producing millions more of red blood cells in the bone marrow (their normal site of production) and this expands the bone plates leading to malformations and impaired growth. The spleen and liver pitch in, trying to help, but grow abnormally, making matters worse. Untreated thalassemics will end up being like the little Greek boy described earlier. Diagnosis is typically made in the first few months of life and if treatment starts early on a regular program, virtually all these symptoms can be averted.
- Bone Marrow Transplant
High dose chemotherapy (bone marrow poisons) is given to a child to kill all cells in the marrow – the good, the bad – including thalassemia-affected red cells. Then normal bone marrow cells from another ‘matching’ donor are infused into the patient and eventually the patient will start growing normal blood cells. The donor stem cells can also be obtained from newborns’ placentas (cord blood transplantation) and that has some advantages. As of now, this is the only known ‘cure’ for thalassemia. In major centres of the West, cure rates as high as 95% are reported. Finding a donor who is a good match is very difficult if there are no siblings and in a genetically diverse population such as Indians.
- Red Blood Cell Transfusion
Regular, periodic transfusions are the mainstay of treatment. Since the body cannot make normal hemoglobin, normal hemoglobin is provided via the transfusions to maintain a hemoglobin level above 9 gm percent. If instituted early with due care, patients can lead virtually normal lives without symptoms for decades. With modern blood banking techniques this has become safer and more effective than ever before. In spite of this, complications may arise and frequently may cause more havoc than the disease itself.
Hydroxurea and others like it have been tried in an attempt to stimulate other ‘normal’ variants of hemoglobin in the body and decrease transfusion needs. So far, the results have been disappointing.
- Gene therapy
Inserting a normal gene into the chromosome within a living cell, to knock out the abnormal gene is called gene therapy. Since thalassemia is caused by a specific genetic defect, this procedure may provide the ultimate cure in the future. Exciting progress has been made in the technology and there is early success in animal experiments.
Periodic blood transfusions bring many problems. The major one is iron overload. Every bag of blood infuses about 250 mg of iron into the body and the human body has no mechanism for normal excretion of iron. In addition, thalassemics absorb more iron from their food. Eventually iron accumulates in normal tissues leading to endocrine problems, growth retardation, heart failure and death. Most thalassemics die in their twenties, not from their disease, but from iron overload and heart failure. Thalassemics need to limit iron in their diet and also take less vitamin C containing foods since antioxidants increase iron absorption and deposition. Blood transfusions can also cause HIV, Hepatitis C, Hepatitis B, CMV infections although these are now rare with modern blood banking.
There is no simple, effective long-term solution for thalassemia and it is best prevented. General awareness is vitally important. Consanguineous marriages, especially within high-risk communities, are a major cause of the disease. Pre-marital screening by a simple blood test can be considered in such cases. In known thalassemics or those with a ‘trait’ wishing to have a baby, proper genetic counseling is a must and the odds of the baby being involved must be clearly discussed. Pre-natal testing is the process of finding out if the foetus within a mother’s womb has the disease, upon knowing which, the parents can choose to have the pregnancy terminated. This is a specialist service available at select centres in India. For a very problematic disease like thalassemia an ounce of prevention can go a lot farther than a pound of treatment.